US5745072A - Method and apparatus for precise noncoherent doppler tracking of a spacecraft - Google Patents
Method and apparatus for precise noncoherent doppler tracking of a spacecraft Download PDFInfo
- Publication number
- US5745072A US5745072A US08/717,395 US71739596A US5745072A US 5745072 A US5745072 A US 5745072A US 71739596 A US71739596 A US 71739596A US 5745072 A US5745072 A US 5745072A
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- United States
- Prior art keywords
- spacecraft
- frequency
- signal frequency
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- ground station
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
- G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
- G01S13/765—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted with exchange of information between interrogator and responder
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/50—Systems of measurement based on relative movement of target
- G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/50—Systems of measurement based on relative movement of target
- G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
- G01S13/60—Velocity or trajectory determination systems; Sense-of-movement determination systems wherein the transmitter and receiver are mounted on the moving object, e.g. for determining ground speed, drift angle, ground track
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/003—Transmission of data between radar, sonar or lidar systems and remote stations
Definitions
- the invention relates to spacecraft Doppler tracking and, more specifically, is a method and apparatus for canceling space-craft oscillator drift effects during two-way noncoherent tracking to provide a spacecraft velocity measurement within a 0.1 mm/second degree of accuracy.
- an uplink carrier is transmitted from the ground at a frequency f t , the spacecraft transponder multiplies the received frequency by a factor of ⁇ , and transmits a downlink carrier at this frequency.
- the uplink and downlink frequencies are Doppler-shifted by the spacecraft motion.
- the frequency received on the ground is ##EQU1## where c is the speed of light and v is the rate of change of the distance between the spacecraft and the ground station. Because f t and ⁇ are known on the ground, the Doppler component of this signal can be extracted. This can be done to a high degree of accuracy assuming that the ground oscillator frequency (f t ) is highly stable over the round-trip propagation time. A stability of 1 part in 10 13 is typically adequate.
- transponders utilizing coherent tracking are typically heavy and expensive to build. Furthermore, the coherency requirement is a barrier to revolutionary changes in transponder design.
- the spacecraft For a noncoherent velocity measurement, the spacecraft generates a downlink signal at a frequency f d that is not coherent with the uplink signal.
- the signal received on the ground is then ##EQU2## where f d is measured in a ground reference frame.
- f d is measured in a ground reference frame.
- a frequency error in the knowledge of f d of only 1 part in 10 10 will result in a velocity error of a few centimeters per second. This is an unacceptable error if it cannot be accurately removed from the measurement.
- Previous ideas for noncoherent navigation have been limited either by spacecraft oscillator stability or have required changes to ground station equipment to support special downlink signaling formats designed to cancel spacecraft oscillator drift.
- the method and apparatus of the invention provide for simplification of spacecraft hardware by establishing a new approach for Doppler tracking of the spacecraft radio signals. This new approach permits the transponder to be broken into separate transmitter and receiver elements, with the Doppler tracking performed noncoherently.
- a measurement of the received uplink frequency, f u is made in the spacecraft relative to an on-board oscillator.
- the same oscillator is used to generate the downlink signal, f d .
- the on-board measurement is telemetered to the ground and used to correct the two-way Doppler measurement made by the ground station. Spacecraft oscillator drift rate effects are cancelled out in the process.
- the invention provides for 0.1 mm/second accuracy with no required changes to ground station hardware.
- Other advantages of the invention include:
- Non-critical on-board oscillator requirements i.e., an ultra-stable oscillator is not necessarily required.
- FIG. 1 illustrates the overall system concept which includes the invention for precise noncoherent Doppler tracking of a spacecraft.
- FIG. 2 is a block diagram illustrating a typical spacecraft hardware implementation of the invention.
- FIG. 3 is a graph illustrating the results of a specific implementation of FIG. 2.
- the two-way, noncoherent Doppler tracking method of the invention is based on the idea that the uplink and downlink signals can be compared within the spacecraft and this information can be used to correct the Doppler measurement made on the ground to determine the velocity of the spacecraft.
- a key aspect of the invention then is making a measurement on-board the spacecraft that is related, through known parameters, to the ratio of the uplink signal, f u , received by the spacecraft and the transmitted downlink signal, f d , and including this information within the spacecraft telemetry for use in precisely determining the spacecraft velocity on the ground.
- FIG. 2 shows a hardware implementation of the invention.
- the spacecraft oscillator outputs a signal that is used for generating the downlink frequency, f d , as well as reference frequencies, ⁇ f d and ⁇ f d ,for the downconversion and counting processes.
- Zero-crossings of the downconverted received signal are then counted by counter #1.
- Counter #2 is used to count zero-crossings of a reference frequency, ⁇ f d , related to the downlink signal.
- counter #1 After counter #1 reaches a predetermined number of counts it will stop counter #2.
- the result of this process is a ratio n 2 /n 1 that is related, by known parameters, to the ratio of the received uplink frequency, f u , to the transmitted downlink frequency, f d .
- the value n 1 is predetermined and the measured value n 2 is transmitted to the ground in the spacecraft telemetry.
- the resolution of the n 2 measurement is increased by downconverting (linearly translating) the uplink signal to as low a frequency as possiblebefore using it to drive counter #1.
- This effect is illustrated by the following example.
- counter #1 is running at a 2 GHz frequencyunder zero velocity conditions. If a Doppler shift of +2 MHz occurred, thenthe counter would be operating at a frequency that is 0.1% higher. If the 2GHz signal was linearly translated to 200 MHz before driving counter #1, then a Doppler shift of +2 MHz would represent a 1.0% increase in frequency instead.
- the n 2 count is equal to (f counter 2/f counter 1)n 1 , its resolution is directly related to the sensitivity of the counter #1 frequency to Doppler shifts. For the above example, we have increased the resolution of counter #2 by a factor of 10.
- n 2 The output count, n 2 , will be ##EQU3##where f d is the downlink frequency transmitted by the spacecraft, f t is the uplink frequency transmitted by the ground station, f u is the uplink frequency received by the spacecraft, v is the rate of changeof the distance between the spacecraft and the ground station, and ⁇ is an error term due to the quantization effect of counter #2.
- the impact of this error term, which varies randomly between +1, can be made as small as desired by making n 1 , large; therefore, it will be dropped from further calculations. It is easily included in the final result if desired.
- the output count, n 2 which is related through known parameters to the ratio of the received uplink and transmitted downlink frequencies, will be included within the spacecraft telemetry andused to correct the velocity measurement by correcting for spacecraft oscillator drift rate effects in the two-way Doppler measurement made by the ground station.
- a significant advantage of this invention over other noncoherent techniques is that it requires no changes to the ground station hardware.
- the ground system processes the downlink signal as if it was coherent with the uplinksignal.
- the velocity measurement made on the ground will be in error, but by an amount that can be determined by the spacecraft count. In this way, the velocity measurement on the ground does not require a change in hardware or procedures, except to impose a correction based upon spacecraft telemetry.
- Equation (3) is the frequency received at the ground station. This estimate is in error due to lack of precise knowledge of the spacecraft frequency f d .
- the true velocity may be recovered from the raw measurement (v non ), the measured value of n 2 , and the known parameters n 1 , ⁇ , ⁇ , and ⁇ y as: ##EQU7##In this way, a velocity measurement made with existing equipment and procedures can be corrected with the aid of telemetry information to produce an accurate velocity measurement with a two-way, noncoherent system.
- the invention results in a Doppler measurement that is independent of spacecraft oscillator frequency drift without the need for a USO. Furthermore, using the measurements described above, the frequency of the spacecraft oscillator can be inferred on the ground. Through a series of such inferences, the drift rate of the oscillator can be determined in-flight. This will provide for periods of accurate one-way Doppler tracking during periods when two-way tracking is not available (such as during ground transmitter outages).
- the invention also eliminates two-way radio noise from the tracking system.This noise can degrade the tracking accuracy, particularly in systems that use two frequency bands such as X-band for the uplink and Ka-band for the downlink.
- FIG. 2 has been suitably annotated with corresponding counter and local oscillator frequencies.
- the frequency of counter #1 (201.36 Mhz) is relatively low compared to the frequency of counter #2 (1054.76 MHz), a desirable feature.
- Other pertinent parameters for our example are listed in Table 1.
- the invention provides for a comparison of the uplink and downlink frequencies on board a spacecraft in such a way that precise velocity measurements may be made with a two-way noncoherent system, thus eliminating much of the frequency multiplication and division present in coherent transponders. This will allow for the replacement of existing coherent transponders with a simpler system so as to reduce the cost and weight of the spacecraft electronics. Furthermore, the use of the invention need not result in any change in the existing ground system. Only a correction to the measured velocity, contained in telemetry information received by the ground station, is required.
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- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
Description
TABLE 1 ______________________________________ Parameters for example implementation Parameter Value ______________________________________ α 880/749 β 7/8γ 1/8 n.sub.1 2.sup.33 ______________________________________
Claims (10)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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US08/717,395 US5745072A (en) | 1996-09-20 | 1996-09-20 | Method and apparatus for precise noncoherent doppler tracking of a spacecraft |
US09/066,516 US5995039A (en) | 1996-09-20 | 1998-04-24 | Method and apparatus for precise noncoherent doppler tracking of a spacecraft |
Applications Claiming Priority (1)
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US08/717,395 US5745072A (en) | 1996-09-20 | 1996-09-20 | Method and apparatus for precise noncoherent doppler tracking of a spacecraft |
Related Child Applications (1)
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US09/066,516 Continuation-In-Part US5995039A (en) | 1996-09-20 | 1998-04-24 | Method and apparatus for precise noncoherent doppler tracking of a spacecraft |
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US08/717,395 Expired - Lifetime US5745072A (en) | 1996-09-20 | 1996-09-20 | Method and apparatus for precise noncoherent doppler tracking of a spacecraft |
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Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5995039A (en) * | 1996-09-20 | 1999-11-30 | The Johns Hopkins University | Method and apparatus for precise noncoherent doppler tracking of a spacecraft |
WO2002065152A2 (en) * | 2001-02-09 | 2002-08-22 | The Johns Hopkins University | Method and apparatus for non-coherent navigation using low frame rate telemetry |
EP1361457A1 (en) * | 2002-05-07 | 2003-11-12 | Zelinda Ltd | System and method for performing space vehicle range-rate measurements |
US6965753B1 (en) * | 1999-08-31 | 2005-11-15 | Qualcomm Incorporated | Apparatus for performing doppler correction in a wireless communications system |
US7206575B1 (en) * | 2002-12-18 | 2007-04-17 | The Johns Hopkins University | Method of remotely estimating a rest or best lock frequency of a local station receiver using telemetry |
US20120146834A1 (en) * | 2010-12-10 | 2012-06-14 | Karr Lawrence J | Reduced computation communication techniques for location systems |
US20180279246A1 (en) * | 2015-05-28 | 2018-09-27 | Facebook, Inc. | Doppler shift estimation and correction for broadband communication in unmanned aerial vehicles |
CN111693770A (en) * | 2020-06-05 | 2020-09-22 | 中国人民解放军63921部队 | Uplink frequency scanning method for measurement and control station/measurement ship |
RU2749878C1 (en) * | 2020-11-06 | 2021-06-18 | федеральное государственное казенное военное образовательное учреждение высшего образования "Военная академия связи имени Маршала Советского Союза С.М. Буденного" Министерства обороны Российской Федерации | Method for determining orthogonal components of velocity vectors and method for determining coordinates of two space vehicles using earth stations |
RU2750228C1 (en) * | 2020-11-06 | 2021-06-24 | федеральное государственное казенное военное образовательное учреждение высшего образования "Военная академия связи имени Маршала Советского Союза С.М. Буденного" Министерства обороны Российской Федерации | Method for determining orthogonal components of velocity vector and method for determining space vehicle coordinates using earth stations |
RU2791153C1 (en) * | 2022-04-05 | 2023-03-03 | федеральное государственное казенное военное образовательное учреждение высшего образования "Военная орденов Жукова и Ленина Краснознаменная академия связи имени Маршала Советского Союза С.М. Буденного" Министерства обороны Российской Федерации | Method for determining the orthogonal components of the velocity vectors of two spacecraft using earth stations and a radiating reference station |
Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3740671A (en) * | 1972-04-06 | 1973-06-19 | Nasa | Filter for third-order phase-locked loops |
US3860921A (en) * | 1973-11-15 | 1975-01-14 | Nasa | Simultaneous acquisition of tracking data from two stations |
US4001690A (en) * | 1975-08-15 | 1977-01-04 | Rca Corporation | Method and apparatus for compensation of doppler effects in satellite communication systems |
US4060809A (en) * | 1975-04-09 | 1977-11-29 | Baghdady Elie J | Tracking and position determination system |
US4689806A (en) * | 1983-11-07 | 1987-08-25 | Hughes Aircraft Company | Receiver mode control for acquiring and tracking a signal |
US4785463A (en) * | 1985-09-03 | 1988-11-15 | Motorola, Inc. | Digital global positioning system receiver |
US4901368A (en) * | 1987-10-19 | 1990-02-13 | American Telephone And Telegraph Company | Frequency translation correction scheme for satellite communication system |
US5063387A (en) * | 1989-11-20 | 1991-11-05 | Unisys Corporation | Doppler frequency compensation circuit |
US5187805A (en) * | 1989-10-02 | 1993-02-16 | Motorola, Inc. | Telemetry, tracking and control for satellite cellular communication systems |
US5414431A (en) * | 1990-01-02 | 1995-05-09 | Gte Spacenet Corporation | Satellite communication system |
US5594454A (en) * | 1994-04-13 | 1997-01-14 | The Johns Hopkins University | Global positioning system (GPS) linked satellite and missile communication systems |
US5644572A (en) * | 1995-10-03 | 1997-07-01 | Motorola, Inc. | Method and apparatus for approximating propagation delay for use in transmission compensation to orbiting satellites |
-
1996
- 1996-09-20 US US08/717,395 patent/US5745072A/en not_active Expired - Lifetime
Patent Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3740671A (en) * | 1972-04-06 | 1973-06-19 | Nasa | Filter for third-order phase-locked loops |
US3860921A (en) * | 1973-11-15 | 1975-01-14 | Nasa | Simultaneous acquisition of tracking data from two stations |
US4060809A (en) * | 1975-04-09 | 1977-11-29 | Baghdady Elie J | Tracking and position determination system |
US4001690A (en) * | 1975-08-15 | 1977-01-04 | Rca Corporation | Method and apparatus for compensation of doppler effects in satellite communication systems |
US4689806A (en) * | 1983-11-07 | 1987-08-25 | Hughes Aircraft Company | Receiver mode control for acquiring and tracking a signal |
US4785463A (en) * | 1985-09-03 | 1988-11-15 | Motorola, Inc. | Digital global positioning system receiver |
US4901368A (en) * | 1987-10-19 | 1990-02-13 | American Telephone And Telegraph Company | Frequency translation correction scheme for satellite communication system |
US5187805A (en) * | 1989-10-02 | 1993-02-16 | Motorola, Inc. | Telemetry, tracking and control for satellite cellular communication systems |
US5063387A (en) * | 1989-11-20 | 1991-11-05 | Unisys Corporation | Doppler frequency compensation circuit |
US5414431A (en) * | 1990-01-02 | 1995-05-09 | Gte Spacenet Corporation | Satellite communication system |
US5594454A (en) * | 1994-04-13 | 1997-01-14 | The Johns Hopkins University | Global positioning system (GPS) linked satellite and missile communication systems |
US5644572A (en) * | 1995-10-03 | 1997-07-01 | Motorola, Inc. | Method and apparatus for approximating propagation delay for use in transmission compensation to orbiting satellites |
Non-Patent Citations (2)
Title |
---|
J.W.Armstrong et al., "Starprobe: Coronal Plasma Turbulence Effects on Tracking and Telemetry", Presented at the AIAA 20th Aerospace Sciences Meeting, Jan. 11-14, 1982 in Orlando, Florida. |
J.W.Armstrong et al., Starprobe: Coronal Plasma Turbulence Effects on Tracking and Telemetry , Presented at the AIAA 20th Aerospace Sciences Meeting, Jan. 11 14, 1982 in Orlando, Florida. * |
Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5995039A (en) * | 1996-09-20 | 1999-11-30 | The Johns Hopkins University | Method and apparatus for precise noncoherent doppler tracking of a spacecraft |
US6965753B1 (en) * | 1999-08-31 | 2005-11-15 | Qualcomm Incorporated | Apparatus for performing doppler correction in a wireless communications system |
WO2002065152A2 (en) * | 2001-02-09 | 2002-08-22 | The Johns Hopkins University | Method and apparatus for non-coherent navigation using low frame rate telemetry |
WO2002065152A3 (en) * | 2001-02-09 | 2002-12-19 | Univ Johns Hopkins | Method and apparatus for non-coherent navigation using low frame rate telemetry |
US6650279B2 (en) | 2001-02-09 | 2003-11-18 | The Johns Hopkins University | Method and apparatus for non-coherent navigation using low frame rate telemetry |
EP1361457A1 (en) * | 2002-05-07 | 2003-11-12 | Zelinda Ltd | System and method for performing space vehicle range-rate measurements |
US7206575B1 (en) * | 2002-12-18 | 2007-04-17 | The Johns Hopkins University | Method of remotely estimating a rest or best lock frequency of a local station receiver using telemetry |
US20070099565A1 (en) * | 2002-12-18 | 2007-05-03 | Fielhauer Karl B | Method of remotely estimating a rest or best lock frequency of a local station receiver using telemetry |
US20120146834A1 (en) * | 2010-12-10 | 2012-06-14 | Karr Lawrence J | Reduced computation communication techniques for location systems |
US8384584B2 (en) * | 2010-12-10 | 2013-02-26 | Roundtrip Llc | Reduced computation communication techniques for location systems |
US20180279246A1 (en) * | 2015-05-28 | 2018-09-27 | Facebook, Inc. | Doppler shift estimation and correction for broadband communication in unmanned aerial vehicles |
US10687297B2 (en) * | 2015-05-28 | 2020-06-16 | Facebook, Inc. | Doppler shift estimation and correction for broadband communication in unmanned aerial vehicles |
US11234202B1 (en) | 2015-05-28 | 2022-01-25 | Facebook, Inc. | Doppler shift estimation and correction for broadband communication in unmanned aerial vehicles |
CN111693770A (en) * | 2020-06-05 | 2020-09-22 | 中国人民解放军63921部队 | Uplink frequency scanning method for measurement and control station/measurement ship |
CN111693770B (en) * | 2020-06-05 | 2023-02-03 | 中国人民解放军63921部队 | Uplink frequency scanning method for measurement and control station/measurement ship |
RU2749878C1 (en) * | 2020-11-06 | 2021-06-18 | федеральное государственное казенное военное образовательное учреждение высшего образования "Военная академия связи имени Маршала Советского Союза С.М. Буденного" Министерства обороны Российской Федерации | Method for determining orthogonal components of velocity vectors and method for determining coordinates of two space vehicles using earth stations |
RU2750228C1 (en) * | 2020-11-06 | 2021-06-24 | федеральное государственное казенное военное образовательное учреждение высшего образования "Военная академия связи имени Маршала Советского Союза С.М. Буденного" Министерства обороны Российской Федерации | Method for determining orthogonal components of velocity vector and method for determining space vehicle coordinates using earth stations |
RU2791153C1 (en) * | 2022-04-05 | 2023-03-03 | федеральное государственное казенное военное образовательное учреждение высшего образования "Военная орденов Жукова и Ленина Краснознаменная академия связи имени Маршала Советского Союза С.М. Буденного" Министерства обороны Российской Федерации | Method for determining the orthogonal components of the velocity vectors of two spacecraft using earth stations and a radiating reference station |
RU2803662C1 (en) * | 2023-03-02 | 2023-09-19 | Федеральное государственное казенное военное образовательное учреждение высшего образования "Ярославское высшее военное училище противовоздушной обороны" Министерства обороны Российской Федерации | Method for determining coordinates of spacecraft using earth stations and emitting benchmark station |
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